Plants are often genetically specialized as ecotypes attuned to local environmental conditions. When conditions change, the optimal environment may be physically displaced from the local population, unless dispersal or in situ evolution keep pace, resulting in a phenomenon called adaptational lag. Using a 30-year-old reciprocal transplant study across a 475 km latitudinal gradient, we tested the adaptational lag hypothesis by measuring both short-term (tiller population growth rates) and long-term (17-year survival) fitness components of Eriophorum vaginatum ecotypes in Alaska, where climate change may have already displaced the optimum. Analyzing the transplant study as a climate transfer experiment, we showed that the climate optimum for plant performance was displaced ca. 140 km north of home sites, although plants were not generally declining in size at home sites. Adaptational lag is expected to be widespread globally for long-lived, ecotypically specialized plants, with disruptive consequences for communities and ecosystems.

Although shale drilling operations for oil and natural gas have increased greatly in the past decade, few studies directly quantify the impacts of shale development on plants and wildlife. We evaluate knowledge gaps related to shale development and prioritize research needs using a quantitative framework that includes spatial and temporal extent, mitigation difficulty, and current level of understanding. Identified threats to biota from shale development include: surface and groundwater contamination; diminished stream flow; stream siltation; habitat loss and fragmentation; localized air, noise, and light pollution; climate change; and cumulative impacts. We find the highest research priorities to be probabilistic threats (underground chemical migration; contaminant release during storage, during disposal, or from accidents; and cumulative impacts), the study of which will require major scientific coordination among researchers, industry, and government decision makers. Taken together, our research prioritization outlines a way forward to better understand how energy development affects the natural world.

American ginseng (Panax quinquefolius L.) is an uncommon to rare understory plant of the eastern deciduous forest. Harvesting to supply the Asian traditional medicine market made ginseng North America's most harvested wild plant for two centuries, eventually prompting a listing on CITES Appendix II. The prominence of this representative understory plant has led to its use as a phytometer to better understand how environmental changes are affecting many lesser-known species that constitute the diverse temperate flora of eastern North America. We review recent scientific findings concerning this remarkable phytometer species, identifying factors through its history of direct and indirect interactions with humans that have led to the current condition of the species. Harvest, deer browse, and climate change effects have been studied in detail, and all represent unique interacting threats to ginseng's long-term persistence. Finally, we synthesize our current understanding by portraying ginseng's existence in thousands of small populations, precariously poised to either escape or be drawn further toward extinction by the actions of our own species.

Bioclimatic envelope models of species' responses to climate change are used to predict how species will respond to increasing temperatures. These models are frequently based on the assumption that the northern and southern boundaries of a species' range define its thermal niche. However, this assumption may be violated if populations are adapted to local temperature regimes and have evolved population-specific thermal optima. Considering the prevalence of local adaptation, the assumption of a species-wide thermal optimum may be violated for many species. We used spatially and temporally extensive demographic data for American ginseng (Panax quinquefolius L.) to examine range-wide variation in response of population growth rate (λ) to climatic factors. Our results suggest adaptation to local temperature, but not precipitation. For each population, λ was maximized when annual temperatures were similar to site-specific, long-term mean temperatures. Populations from disparate climatic zones responded differently to temperature variation, and there was a linear relation between population-level thermal optima and the 30-year mean temperature at each site. For species that are locally adapted to temperature, bioclimatic envelope models may underestimate the extent to which increasing temperatures will decrease population growth rate. Because any directional change from long-term mean temperatures will decrease population growth rates, all populations throughout a species' range will be adversely affected by temperature increase, not just populations at southern and low-elevation boundaries. Additionally, when a species' local thermal niche is narrower than its range-wide thermal niche, a smaller temperature increase than would be predicted by bioclimatic envelope approaches may be sufficient to decrease population growth.

Ecotypic differentiation reduces climatic niche breadth at the population level relative to a species' spatial distribution. For species that form climatic ecotypes, if future climate exceeds local population tolerance, climate change will precipitate the decline of extant populations range-wide. Here, we examine the variation in physiological and morphological traits of Eriophorum vaginatum L. collected from a 30-year-old reciprocal transplant experiment, in which six populations of E. vaginatum were transplanted along a latitudinal gradient from Eagle Creek to Prudhoe Bay, Alaska. We tested for ecotypic differentiation of photosynthesis, respiration, chlorophyll fluorescence, and biomass per tiller, which is a metric correlated with population growth in E. vaginatum. The light-saturated photosynthetic rate (A max ) showed homesite advantage in that tussocks in their homesites had significantly higher values of A max relative to nonlocal populations. This pattern of homesite advantage was also observed for biomass per tiller, but not for fluorescence and respiration. Photosynthetic rate was positively correlated with biomass per tiller and survival, suggesting that adaptations related to photosynthesis may optimize performance of local populations to homesite conditions. Taken together, these findings indicate that a rapidly changing climate may elicit population decline of E. vaginatum, rendering this species at a competitive disadvantage to shrubs and boreal forest species, which are expanding northward as the climate changes. Transition from tussock-sedge tundra to boreal forest and shrubland alters features, such as albedo, soil temperature, and water-table depth, in ways that may accelerate climate change.Résumé : La différenciation écotypique réduit l'ampleur de la niche climatique au niveau populationnel relativement à la distribution spatiale d'une espèce. En ce qui concerne les espèces qui forment des écotypes climatiques, si le climat futur excède la tolérance de la population locale, le changement climatique précipitera le déclin des populations qui subsistent sur une large étendue. Les auteurs examinent ici la variation des traits physiologiques et morphologiques d'Eriophorum vaginatum L. récolté dans le cadre d'une expérience de transplantation réciproque pendant 30 ans, dans laquelle six populations d'Eriphorum vaginatum ont été transplantées en fonction d'un gradient latitudinal allant de Eagle Creek à Prudhoe Bay, en Alaska. Les auteurs ont testé la différenciation écotypique de la photosynthèse, de la respiration, la fluorescence de la chlorophylle et la biomasse par talle, une métrique qui est en corrélation avec la croissance de la population chez E. vaginatum. Le taux de photosynthèse en fonction de la densité du flux de lumière (A max ) révélait un avantage de l'habitat d'origine car les buttes gazonnées à leur lieu d'origine présentaient des valeurs d'A max supérieures à celles des populations non locales. Ce patron d'avantage de l'habitat d'origine a aussi été observé sur le plan de la bio...